In Depth Model Discussion, Analysis and Summaries

[phil nw.]

Yes looking at the MJO current state and forecasts this pattern is going nowhere fast.

Suggestions it will re-emerge in either phase 8 or phase 1 in 10+ days would mean a continuation of this pattern,ie Atlantic trough close by and the Euro block going nowhere fast.

Any movement of MJO into phase 3 looks temporary thus any pressure rise across the UK in about a weeks time probably would be short lived and we will likely be back to our mild Southerly biased Atlantic flow as the trough edges in again.

Edited October 29, 2011 by phil n.warks.

[chionomaniac]

Yes looking at the MJO current state and forecasts this pattern is going nowhere fast.

Suggestions it will re-emerge in either phase 8 or phase 1 in 10+ days would mean a continuation of this pattern,ie Atlantic trough close by and the Euro block going nowhere fast.

Any movement of MJO into phase 3 looks temporary thus any pressure rise across the UK in about a weeks time probably would be short lived and we will likely be back to our mild Southerly biased Atlantic flow as the trough edges in again.

Hi Phil,

Looking at all the models MJO forecasts there is a fair bit of divergence creeping in. For instance the Canadian model has things heading towards phases 4 and 5 whilst the NCEP ensemble suite has us heading back towards phases 8-1. So this is worth monitoring presently.

[sebastiaan1973]

I loved that last part of your post.

'then the second half of the winter could be, interesting.'

Sorry, I'm too much of a novice to add anything of interest to this thread, I just stick to the normal model output discussion but I thought I would point something out.. That last phrase you posted just put a smile on my face. All that's missing from the end of that is a . Thank you

Did you ask Paul's permission for that?

That video could be copyrighted.

No worry, I gave the netweather link, so they can click, and they will get to to the Netweather site, I really don't see any problems with that

[phil nw.]

Hi Phil,

Looking at all the models MJO forecasts there is a fair bit of divergence creeping in. For instance the Canadian model has things heading towards phases 4 and 5 whilst the NCEP ensemble suite has us heading back towards phases 8-1. So this is worth monitoring presently.

Hi Chiono,

Yes i see even on the NCEP some GFS members show that,but taking the mean the trend at present looks like heading to 8 or 1.

Of course as with the sypnotic output these can change when we are looking beyond 8-10 days.

The MJO is now weakening and it will be a few runs before we will know for certain where the convection goes i suppose.

Edited October 30, 2011 by phil n.warks.

[summer blizzard]

Surely with a weaker MJO wave, it could allow La Nina to take over?

[phil nw.]

Surely with a weaker MJO wave, it could allow La Nina to take over?

Hi SB,

I think it`s usual for the MJO wave to weaken somewhat(less convection)as it moves Eastwards towards the cooler waters of the Eastern Pacific.

La Nina is already showing it`s hand as i sure you are aware,although only moderately this Autumn (around -0.7C ) but may strengthen a little more.

I am no expert on the dynamics between the relative strengths and effects between MJO and La Nina but this Wiki. link may be usefull to you.

http://en.wikipedia....ian_oscillation

I am sure Stuart(GP) can add much more information than me,if he has time.

I am not sure if there is anything in the learning area on any links between the 2.

All i can ascertain is that La Nina is a standing pattern-ie.a cooler area of Ocean-which exists for a year or two whereas the MJO is an Eastward progression of tropical convection and rainfall around the tropics -usually starting in the Indian Ocean--over a cycle of 40-60 days.

How this convection reacts influences weather patterns further afield creating atmospheric(Rossby)waves

http://en.wikipedia....ki/Rossby_waves

Studies of this cycle of convection over many years has enabled meteorologists to create snapshots(composites) of the global atmosphere,s average upper air patterns when the MJO enters a particular area of the tropics.

I hope this helps.

Edited October 30, 2011 by phil n.warks.

[mcweather]

I,m not sure if anyone has picked up on this yet from Matt Hugo. Meteorologist at Weather Commerce. He has access to the ECM 32 day output and posted this over on Two yesterday morning.

Morning all...

Well I hold good news, well depending on your terminology of good news that is. I've looked at the latest EC 32 day info this morning and the signal for a pattern change later in November and into early December is still there and in a big way!

Up to the middle of month high pressure persists to the E and this maintains relatively mild conditions, driest in the E, wettest in the W etc. However, beyond mid-month what the model is signalling is for high pressure to migrate and there is then the development of a +ve pressure anom to the N or NW of the UK during the final week of November and into early December, as low pressure becomes dominant to the S. In essence the final week of the 32 day forecast is signalling a pattern similar to that of last year with E or NE'lies across the UK and there is a dramatic drop in temperature forecast during the final quarter of the forecast period.

Clearly I put emphasis on this model signalling a potential pattern change this time last week and whilst any longer term model is open to change, I do have quite a decent liking to this model as it has picked up trends at times throughout this year weeks in advance. Clearly this post will be fascinating to read and come back to in around 3 weeks time to see what is actually on the horizon for the end of November, but IF this model is picking up this pattern change correctly then it would seem that another dramatic turn-around to something far more wintry is likely towards the end of November onwards...

Time will tell!...

Matt.

Matthew Hugo BSc(Hons), FRMetS

Meteorologist

Weather Commerce Ltd

On Twitter @MattHugo81

Interesting developments could be afoot but as ever patience will be required. I would imagine that if this pattern change is still showing up next week that the Meto 30 dayer could turn out to be an interesting read when it is updated next friday. I would add that my experience of Matts post is that he is very measured and not given to cold and snow ramping.

Edited November 5, 2011 by mcweather

[dallas]

Maybe we will start to see some signs of this on the GFS in a week or so

[Glacier Point]

Interesting..

As per today's 00z data run, a significant mountain torque centred mainly over the Himalayas has introduced a massive surge of westerly winds across 30N (and corresponding increase in the southern hemisphere).

Tendency in relative angular momentum has shot upwards, registering a massive -4 to +4 SD in the space of 2 weeks.

That's good support for anomalous ridges to develop in the high middle latitudes.

With La Nina running around -0.8C, we should see a corresponding removal in westerlies in the next 5-10 days resulting in a big negative tendency in relative angular momentum sending the global wind oscillation through phase 4-8 orbit, also helping to sustain an amolous ridge solution Scandinavia - Iceland - northern UK.

Problems still persist with the depth of the ridge which has its roots in North Africa and will take sustained pressure to remove it. I think a good 10 day spell of the ridge currently to our east strengthening and shifting its position north and north-west, possibly as the pattern relaxes with the Atlantic trough re-setting at the end. That will bring about a large chunk of cold air getting displaved down the eastern side of the anomalous ridge into Russia and potentially getting dragged over the eastern Med. For the UK, settling down with high pressure. Daytime values continuing above average, night time fog and frost becoming increasingly common.

One longer term feature to monitor will be stratospheric temperatures. Mountain torques such as this can lead to wave breaking so it will be worth keeping an eye out for these over the next 10 days.

[Snowstorm1]

Was that a little ramp GP :o

[chionomaniac]

There has been nothing suggested on the stratospheric charts since the Asian mountain torque started. From previous years experience any wave has travelled up to the top of the stratosphere, broken into the vortex at that point before rebounding back down again.

This is the only chart that I can find that could indicate this:

The T+240 chart here doesn't seem to follow.

[BLAST FROM THE PAST]

I suggest that what we are begiining to see are the teleconnections beginning to respond to external drivers. Once the dust and transition eventually settles we'll see what I think will be a cold pattern set in for late Nov. The teleconnections did not suggest this and I suspect GP did not suspect that he would be looking at such a potential change?

BFTP

[Snowmad79]

7 days ago we were looking at an "ensconsed pattern" as GP said in the previous update and one that was not looking like changing. 8 days on and things are looking a bit different.

I dont think ive seen the AM Tendancy chart go so negative and then shoot so positive straight after which looks off the chart. But what I have noticed in the past 2 yrs now for this time of year is a surge in + tendancy is usually followed by poleward movement of wind anomiles and then blocking at high lattitudes. Not sure if this is casual phenomenen at this time of year as I've only been looking at those charts for 2 yrs, does seem like pattern to me though.

[Glacier Point]

Think I can answer the two posts above this way.

A sneak preview of the draft base analogue we will be using as guidance for the winter forecast showing December H5 anomalies.

That's not too dissimilar to what we have had as the ensconsed pattern, trough to our west, ridge to our east.

Ah, but how can we use this if the models continue to evolve the development of a ridge towards Greenland from Scandinavia ? Well. take a look at the base analogue for November:

Remembering any changes will be in the 6-10 day timeframe, we will have anything between 11 and 15 days 'pattern' in the bank. Also taking into account the ECM mean H5 at day 10 highlights the difficulty in cold being advected fully towards western Europe, I would favour odds on the end November anomaly looking not too far off the analogue.

This is not too far removed from last November's pattern except that the mean ridge is placed much further east this time and we are stuck on the 'wrong' side for cold.

Remembering also that the polar stratosphere is running anomalously cold right now, and the likely migration of the polar vortex towards the Canadian Arctic during December.

So in summary, the very strong mountain torque event and consequent sharp increase in tendency in relative angular momentum definately spices things up in the medium term, although I suspect the default troughing to our west and the developing ridge over Scandinavia will not be far off a return in December as the main feature of our weather.

Edited November 6, 2011 by Glacier Point

[Alex]

Also noticed the NAO which is forecasted to dip slightly away in the coming 14days may possibly help a breakdown to the current pattern?

Edited November 6, 2011 by Alex

[lorenzo]

NAO Tanking negative on that latest chart...

Also comparing last years MJO phase space to this years current position could easily be extrapolated as we are entering what was 2010 run of events a month later..

Some interesting animations here especially the 90, 30 day mean height illustrations

http://www.esrl.noaa.gov/psd/map/clim/glbcir.quick.shtml#anim

[summer blizzard]

MEI confirms that La Nina was at -0.968 during October so November and December will likely be moderate La Nina months.

I suspect that without any reasonable response from the stratosphere as yet, we will likely see the ridge much closer to the UK but no major cold outbreak for the moment. Given the stratospheric lag of around 20 days as well, it could be early December before we see a real gain from it even if we do see a stratospheric response.

[lorenzo]

Just noticed within the MJO plots on CPC the long range MJO outlook is included.

This is updated every Thursday from the ECMF model with 51 ensembles, the only place I can see a product of this fabled ECMF 32 day out look anywhere other than there own website.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/index.primjo.html

This run sees the MJO run through phase 2 - 3 for end Nov and early December.

Am sure that pattern is readily familiar.

For later in the run HP elongates and the mid atlantic trough weakens.

[sebastiaan1973]

Lorenzo thanks! Where do we find these composite charts for the several different phases?

[lorenzo]

Lorenzo thanks! Where do we find these composite charts for the several different phases?

The composites are here http://raleighwx.americanwx.com/MJO.html

The first list shows composites relative to La Nina years , then the opposite , then the phases of each month.

This is the link for the NOAA site http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

Weekly update http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.ppt

NB Do not take these composites as certainties, the Pacific shows a classic Nina signature at present, whereby on our side of the world this signature is less definitive.

[summer blizzard]

Signs of a change afoot in early December??

For the past month or so we have seen a -PNA pattern in place promoting an eastern USA ridge and Atlantic Trough which has in turn corresponded to a Scandinavian High.

While the change looks slow, it does look as though the pattern over the USA may be changing to a +PNA one which should enable the Scandinavian high to retrogress either over the UK or into the Atlantic in early December.

Given that the AO looks positive i would be inclined to lean towards a high pretty much over us rather than to the west however this may not be a bad pattern to enter into in my opinion and should provide much better scope for retrogression when we do see the stratosphere play ball.

Any opinions?

[lorenzo]

Am glad that at the medium to longer term someone else has spotted the AO trend in future runs. Thought I was going insane when I posted the link earlier from Huffmans main site for MJO variables.

Couple this with Old Met Mans posts about how quickly the stalemate dropped then there are still massive changes hidden in plain sight, looking within each 4 hour period at GFS will never reveal this.

Am sure GP will provide an update soon on the other more exotic TCs including the Strat and GLAAM forcing. For me would really like to see some SST analysis related to cold in light of the NASA article I found earlier today.

Hints at warmer NAtlantic SST giving rise to higher blocking...? Interesting something had to explain the nosebleed greeny highs of last november.

[summer blizzard]

Am glad that at the medium to longer term someone else has spotted the AO trend in future runs. Thought I was going insane when I posted the link earlier from Huffmans main site for MJO variables.

Couple this with Old Met Mans posts about how quickly the stalemate dropped then there are still massive changes hidden in plain sight, looking within each 4 hour period at GFS will never reveal this.

Am sure GP will provide an update soon on the other more exotic TCs including the Strat and GLAAM forcing. For me would really like to see some SST analysis related to cold in light of the NASA article I found earlier today.

Hints at warmer NAtlantic SST giving rise to higher blocking...? Interesting something had to explain the nosebleed greeny highs of last november.

In regards to the sea surface temperature anomalies (we have a thread in the seasonal section) it is about the placement of the anomalies that is most important.

For a -NAO signature you generally want warm anomalies south of Greenland and cold anomalies underneath.

We currently have a rather mixed picture in the Atlantic although the Pacific Jet Stream should amplify in a few weeks if the anomalies have any say.

[Snowmad79]

In regards to the sea surface temperature anomalies (we have a thread in the seasonal section) it is about the placement of the anomalies that is most important.

For a -NAO signature you generally want warm anomalies south of Greenland and cold anomalies underneath.

We currently have a rather mixed picture in the Atlantic although the Pacific Jet Stream should amplify in a few weeks if the anomalies have any say.

Ive been watching NOAA sst anomaly charts for the end of Sept/Oct and the latest available, the seas to our west should be cooling but are warming, a cool pool continues to develop way out accross the atlantic but what else I've noticed is that the seas around the southern tip of Greenland are indeed anomalously warm and continue to warm which is another positive point to note.

[lorenzo]

Had another look at the PNA pattern for an upstream change to the current repeat until fade proceedings

http://raleighwx.americanwx.com/models/12zallpna.gif

Continued motion from the heavily negative to positive. How quickly would this in turn modify the flat jet pattern?